The monitoring of a heart rate of a user for example by means of optical sensors is well known. Here, an optical sensor emits light into the skin of a user and the emitted light is scattered within the skin. Reflected light exits the skin and can be detected by an appropriate detector. Based on the received signals from the sensor, the heart rate of a user can be determined.
Heart rate sensors are for example used for fitness applications. Here, the sensors can be worn as a wrist device or as forearm device, or as a device in contact to the skin in any other location of the body. Accordingly, the heart rate sensor will detect the heart rate of the user and can display the detected heart rate on the device or to a connected system such as a display on an electronic appliance.
When the detected heart rate of a user is to be evaluated, a resting heart rate (RHR) is considered as a physiologically meaningful parameter to indicate conditions such as cardio-respiratory fitness or the like. In other words, the resting heart rate (RHR) is a very useful parameter. The resting heart rate RHR may also be used as an indication of physiological stress. Furthermore, based on the resting heart rate (RHR) and the detected heart rate of a user, the calories consumption of a user can be determined or predicted in a personalized way, thus more accurately. The resting heart rate can also be used as a predictor of the treatment effectiveness in patient's post-myocardial infarction or in patients following a rehabilitation program. The resting heart rate can also be used to evaluate the intensity of physical activities such as walking, running, cycling or the like. Here, the difference between the detected heart rate and the resting heart rate is used to determine the energy expenditure and cardio-respiratory fitness.
There are several ways to determine the resting heart rate. The resting heart rate is typically determined when a user is laying down or is at rest like in a sitting or supine position. Typically, consumption of caffeine and food is avoided and the resting heart rate is determined in the morning. This procedure is cumbersome and obtrusive as it requires refraining from eating and drinking for a sufficiently long period of time and laying down for some time in order to determine the resting heart rate.
US 2014/0066782 A1 discloses a system for determining a resting heart rate of a user. Physical signals from the user are received and monitored to identify valid heart beats. Based on the valid heart beats, a heart rate signal is determined. The heart rate signal is analyzed to identify baseline data points from the series of data points. The resting heart rate is calculated based on the base line data points.